But deputies have now identified a primary suspect, 60-year-old Dennis Brantner, because of tangible evidence that was recently analyzed a second time.

Fink said that the evidence now places Brantner inside Beck's van.

"We have tangible, physical evidence to put a prime suspect ... intimately in the interior of the van," Fond du Lac County Sheriff Mick Fink said.

Brantner is believed to have been a trucker at the time of the crime in 1990. He lives in Kenosha now but lived near Fond du Lac at the time.

Fink said that the crime lab requested photographs of the the man's hands, and a search warrant was issued.

He said Monday that the search warrant was not successfully executed, but photographs were obtained. Fink did not elaborate on how the photographs of the man were obtained.

Beck disappeared while on her way to Appleton for a computer seminar. She was last seen leaving the Forest Mall in Fond du Lac in July 1990.

Her van was found in a store parking lot two days after she was reported missing, with 462 extra miles on the odometer.

Her body was found six weeks later in western Fond du Lac County, and autopsy reports concluded that strangulation and suffocation were the likely causes of death.

Beck's mother talked to WISN 12 News about the new developments in the case.

Diane Beck said Berit's birthday is this weekend, and she said she will never give up looking for her daughter's killer.

"I made a promise at her gravesite that I was going to keep this going as much as I could and for as long as I could," Diane Beck said.

Investigators said they don't have enough evidence to arrest Brantner. Fink said he is hoping that someone remembers something that could help break the case, and hopes Monday's's announcement of new physical evidence may serve as a catalyst.

"This is the best physical evidence we have had in 23 1/2 years of this case," he said. "Somebody remembers. This was a big deal around here and across the state."

Anyone with information is asked to call Fond du Lac's anonymous tip line at 920-906-4777.

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